In a typical consumable electrode arc welding, welding is performed by feeding a welding wire as a consumable electrode at a constant feeding rate and generating an arc between the welding wire and base material. In the consumable electrode arc welding, both the welding wire and the base material are mostly placed in a welding state in which a short-circuiting period and an arc period are alternately repeated.
In order to further improve welding quality, there has been proposed a welding method of alternating feeding of the welding wire between forward feeding and reverse feeding. According to the invention of a patent document 1, an average value of a feeding rate is adjusted according to a welding current setting value, and a repetition frequency and an amplitude of forward feeding and reverse feeding of a welding wire are adjusted to individual values according to the welding current setting value. In the welding method of alternating feeding of the welding wire between the forward feeding and the reverse feeding, a repetition cycle of short circuit and arc can be set to a desired value despite that such the setting is impossible in the related art of the feeding at a constant feeding rate. Thus a generation amount of spatter can be reduced, and improvement of welding quality such as improvement of bead appearance can be achieved.